Although any resistive element interposed in an electrical current path for the purpose of generating a voltage drop proportional to the current flowing through the resistive element may be called a shunt, the term usually applies to what are known as laboratory or bench shunts. Such shunts typically include two rectangular blocks of copper or brass, fitted with provisions for connecting them in an electrical circuit, placed so as to define a gap between these blocks which are bridged by one or more thin, low cross-section elements. The width of the bridging element or elements is selectively trimmed, to produce a predetermined voltage across two binding posts disposed in the blocks on either side of the gap, when a predetermined current is passed through the laboratory or bench shunt. Such shunts are in common use for both measurement, and as part of control systems. However, in control systems, such shunts are often inconvenient and difficult to use, since an event may be intended to occur in response to an event which is only indirectly measured by the shunt, with various factors affecting the relationship between the desired causative event and the current through the shunt in any given application of such a shunt. Since the current-to-voltage proportionality of such a shunt is fixed, either the thin bridging elements must be trimmed, or the resultant voltage signal must be amplified and then selectively reduced in magnitude to provide the desired relationship. The instant invention provides a solution for these and other problems and difficulties in the prior art.